Storing Heat to Make Solar Electricity All the Time

Storing Heat to Make Solar Electricity All the Time

COLOGNE, Germany—At Germany’s aerospace agency, the next frontier is capturing the sun here on Earth and keeping it on tap.

In a 4-year-old glass and steel building near the Cologne-Bonn Airport, researchers at the German Aerospace Center (DLR), Germany’s equivalent of NASA, are working on new ways to produce more heat than light in order to smooth over intermittency, one of the biggest drawbacks of solar power on the grid.

“The focus of this organization is to test ideas as close to production as possible,” said Christos Agrafiotis, a researcher in solar chemical engineering at DLR.

With global solar capacity surging over 200 gigawatts, solar energy is maturing into its technological adolescence. However, it has to start pulling its own weight on the grid instead of relying on elder power sources to bail it out on cloudy days and to step in once the sun sets.

Storing solar energy is one way to make power from the sun a productive member of the grid, especially as utilities work to accommodate photovoltaic panels distributed across rooftops (ClimateWire, Jan. 20).

But battery technology isn’t up to the job just yet in terms of cost and performance to shift solar power across all hours. To keep the electrons flowing even when the sun isn’t shining, many researchers are increasingly looking for better ways to capture and store thermal energy, in concentrating solar plants as well as independent storage systems on the grid.

Concentrating solar plants do have a higher levelized cost of energy compared with photovoltaics, said Thomas Bauer, team leader for thermal process technology at DLR, over the din of compressors in a fabrication shop.

“This is not the full story, because we have a dispatchable system,” he said. “The message is politically not addressed.”

A thermal storage system coupled to a solar plant would make it easier to compete head to head with coal- and natural-gas-fired generators. It would also relieve intermittency anxiety for utilities who have to ramp up generation on cloudy days and sometimes sell electricity at negative prices on especially sunny and windy days… read more at scientificamerican.com